1. Field
The present invention relates to a rechargeable battery.
2. Description of the Related Art
Unlike a primary battery, a rechargeable battery is designed to be recharged by a charging process that changes external electric energy to a chemical energy form and stores the chemical energy and discharged by a discharging process that changes the chemical energy to an electric energy form for use of the electric energy.
Representative examples of a rechargeable battery include a nickel hydrogen battery, a nickel cadmium battery, a lithium ion battery, and a lithium polymer battery.
In general, a rechargeable battery includes an electrode assembly including a positive electrode, a negative electrode, and a separator; a case that houses the electrode assembly; and an electrode terminal that is electrically connected to the electrode assembly and functions as an electrical passage to the exterior of the case. By forming a large capacity battery module by connecting a plurality of rechargeable batteries, the battery module can be used by appliances requiring a large amount of electric power, such as an electric vehicle or a hybrid electric vehicle. In this way, when using a rechargeable battery in an electric vehicle or a hybrid electric vehicle, it is customary to form an electrode terminal using aluminum, copper, etc., in consideration of electrical conductivity and electrochemical corrosion. Additionally, customarily, due to these considerations, the size of the electrode terminal is limited to a predetermined size.
In order to form a battery module from rechargeable batteries, electrode terminals of adjacent rechargeable batteries are connected using a bus bar. When the electrode terminals are formed with aluminum or copper, when fastening the bus bar and the electrode terminals, the bus bar and the electrode terminals cannot be fastened with large torque as a result of the low strength of the electrode terminals.
Thereby, in an environment having much vibration and impact, such as in an electric vehicle or a hybrid electric vehicle, when rechargeable batteries are formed into a battery module, the connection between the bus bar and the electrode terminals (that are fastened with low torque) may be released, causing structural instability of the battery module.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.